The present invention relates generally to gas control valves and more specifically to gas control valves for gas-fired fireplaces or similar installations.
Gas control valves for gas stoves or similar installations are available in a large variety of designs. Said valves are employed to control the gas flow which fuels the burner. For decorative reasons, it is desirable to be able to control the visible flame in fireplaces. It is due to the fitting position of said gas control valves, which is rather unfavorable for frequent adjustment in most of the cases, that as a rule a separate switch is used to switch the main burner on and off.
A solution in which the main burner is switched on and off by means of a separate switch is described in EP 0 635 680 A1, albeit that this option employs a temperature controlled switch. The underlying principle is that the energy captured from the ignition flame by a second thermoelement is employed to regulate a second control valve. The latter control valve opens and shuts off the gas supply of the main burner. In order to do so the above-mentioned thermal switch will either make or break the circuit. Another opportunity, as illustrated in FIG. 2 of the aforementioned European patent application, is to adjust the gas volume by using an electromagnet which actuates a pressure governor.
The disadvantage that is inherent in the solutions described above is the second control valve can only be in two positions, either open or closed. They fail to enable a variable adjustment of the gas volume which flows to the main burner.
Another commonly known fact is that the gas volume which flows to the main burner may be controlled by a DC magnet that actuates on a pressure controller. This solution facilitates the variable adjustment of the gas volume.
However, the disadvantage here is that the required performance parameters of the DC magnet and the fact that each operating state requires electrical energy, make a power supply and additional components necessary, such as rectifiers and transformers.
A further solution is known from electrically-driven gas control devices. There a number of solenoid valves are employed and make on/off positions but also intermediate positions possible.
However, their disadvantage is that they require a power supply as indicated for the solution described further above. To this adds the fact that a power failure prevents operation of the gas-heated fireplace or similar installation.
The present invention is based on the problem of developing a gas control valve of the described kind which facilitates the variable adjustment of the gas volume. In particular, the use of a remote control device shall be facilitated for this purpose. The manufacturing expenditure and the size of the valve shall be kept as small as possible.
The present inventors have found that the problems of the prior art can be addressed by arranging a first valve effecting a stepwise switching on and off and a second valve effecting a modulating control in the casing downstream of the flow path of the gas stream for the main burner, with the valves being controllable jointly by a switch which is biased by a spring element in such a way, that the first valve opens in a jerk-like fashion upon the initial actuation of the switch and, upon the further adjustment of the switch, the second valve is opened progressively. The switch can be actuated by a longitudinally moving tappet which projects from the casing to the outside and whose position can be changed via an operating element. The operating element can be actuated manually and/or via a driving unit in the form of a battery-operated, electrically driven motor.
Thus a solution has been found which removes the disadvantage of the prior art, i.e., a switch without power supply was unable to implement a variable adjustment of the gas volume. The fact that now power is only required when the gas volume shall be adjusted by means of the motor makes it possible to employ a battery, under consideration of a reasonable service life. Further distinguishing features of this solution are its simplicity and its small size.
Confer the other patent claims for further advantageous features of the present invention. What proves to be particularly advantageous is that the axially shiftable operating element is equipped with a radially arranged toothing into which the motor catches via a transmission gear. The rotating motion is limited by stoppers on the casing. A sliding clutch is provided between the driving unit and the operating element in order to prevent overloading of the motor.
In order to optimize the moving range for the adjustment of the gas volume flowing to the main burner, and hence the flame height, it is favorable if the resilient element, which is located between the operating and the tappet, consists of at least two spring elements, with the spring constant of the one spring element being chosen in such a way that it matches the block length when the switching path of the switch is in the range of the jerking switch on/off option. However, when the switching path of the switch is in the modulating control range, both spring elements are in their resilient range. A very simple design can be chosen when the two spring elements consist each of one or more disk springs.
Subsequently, a practical example is given to describe the invention in greater detail.